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Erect hedge-parsley's main stem and side stems give rise to umbels 1.5-2" across of 10-20 umbellets of flowers. Each flower is about 1/8" across consisting of five white petals (often markedly unequal in size), and a creamy white center surrounded by five pink to white stamens. The fruit is an 1/8" long oval covered in hooked hairs to aid in bur-like dispersal; it contains two seeds. (The fruit of common hedge-parsley (Torilis arvensis) has straight or only slightly curved hairs, not hooked, but the hairs are barbed.)

Torilis

Torilis japonica

erect hedge-parsley [Blooms: Jun-Jul]

The apical flowers of prairie trillium have three green sepals that are reflexed so they point down, three maroon petals, six maroon stamens with dark purple anthers incurved toward the center of the flower, and three purple styles with divergent stigmas hidden from view by the stamens. The fruit is a green, six-angled, ovoid berry 1" long; the seeds have an oily food appendage (an elaiosome) that encourages ants to carry them away. Despite the name, prairie trillium does not occur on prairies; it is a shade-loving, woodland plant like the other local trillium, large-flowered trillium (Trillium grandiflorum). Prairie trillium is superficially similar to toadshade (Trillium sessile), but in toadshade the sepals are spread (perpendicular to the stalk), not recurved (parallel to the stalk, pointed down). In addition, the leaves of toadshade are sessile (no petiole) and rarely have the troutlily-like mottling on the leaves that is seen on prairie trillium. The stamens of toadshade are yellow, not maroon. Toadshade does occur in Illinois, but it is less common, and I have yet to see it in Jackson Park.

Trillium

Trillium recurvatum

prairie trillium [Blooms: Apr-May]

Purpletop vervain flowers occur in dense, flat-topped clusters 1-3" across. Individual flowers are about 1/4" (5-6 mm) long and 8-9 mm long. The flowers contain a short, tubular, hairy calyx with five teeth; a pinkish purple, tubular corolla with five spreading lobes that have notched tips; four stamens which do not extend beyond the throat of the flower; and a pistil with a single style. The fruit is four nutlets, cupped in the remnants of the calyx as they mature.

Verbena

Verbena bonariensis

purpletop vervain [Blooms: Sept]

Prostrate vervain stems produce dense spikes of flowers at their tips. Beneath each flower is a 3/4" long, narrow bract with long, whitish hairs; the bracts make up the erect or sprawling flower spike (6" long, 3/4" across), with blooming flowers at the tip and fruits maturing below. Individual flowers are about 1/8" across, with a narrow, very hairy, basal calyx extending into five sharply pointed lobes, and a narrow, tubular corolla that abruptly flares into five rounded lobes ("petals") surrounding a white or greenish-white throat; the upper two lobes are slightly smaller than the lower three. Both the calyx and corolla are the same color whether light blue, purple, or pink. Hidden in the throat of the corolla are four stamens with yellow anthers and a short style. The fruit consists of a capsule containing four nutlets that is nestled in the remains of the calyx. This plant is a pioneer in highly degraded habitats that is especially fond of cracks and crevices — despite its weedy appearance, prostrate vervain is a native species. In spite of the tiny size of its anatomical characters, this is a relatively straightforward plant to confidently identify from the hairy stems, leaves, and flower spikes and the tiny, lavender apical flowers.

Verbena

Verbena bracteata

prostrate vervain [Blooms: Jun-Aug]

Hoary vervain flower spikes are 1-8" long; they are crowded with buds and bluish violet to lavender flowers 1/2" across that open sequentially from the bottom of the spike to the top; below the open flowers are maturing fruits. Individual flowers are tubular, 1/2" long and across, with a grayish green to reddish-purple, hairy calyx sporting five narrow teeth. The tubular, bluish violet to lavender corolla, twice the length of the calyx, abruptly flares into five ovate lobes ("petals"); the two lateral lobes are the largest, while the lower lobe(s) has/have a notched tip. Hidden in the tubular corolla are four recessed stamens with yellow anthers and a single, short green style. The fruits consist of four nutlets held in the remnants of the calyx.

Verbena

Verbena stricta

hoary vervain [Blooms: Jun-Jul]

The tip of a smooth ironweed central stem bears a cluster (a corymb) up to 4" in diameter of magenta composite flowerheads that is quite densely packed in a flat or (sometimes) domed inflorescence. The branches of the inflorescence (but not the stem) may be lightly fuzzy with small hairs. Each flowerhead is 3/4" across and contains 10-30 magenta disk florets, each with five lobes and a very prominent, divided style with curled tips (the stigmas) and five stamens appressed to the base of the style; ray florets are completely absent. The bracts that cover the underside of the flowerheads are green or purplish brown, flattened, appressed, and rounded at their tips, imbricated like fish scales with white, cobwebby hairs around their edges. The fruit is a naked seed with an attached tuft of white hairs (actually, scales). To sort out the Jackson Park ironweeds: (1) if both leaves and stem are densely covered with fine white hairs, the leaves are about 3-4 times longer than wide, and each flowerhead has more than 30 disk florets, it's Missouri ironweed (V. missurica). (2) If both leaves and stems are hairless, there are less than 30 disk florets, and the leaves are narrow (typically a half inch or less; about 6-10+ times longer than wide), it's smooth ironweed (V. fasiculata). (3) If the stems and leaves have only short hairs, there are less than 30 disk florets, and the leaves are about 2" wide and 4-6 times longer than wide, it's tall ironweed (V. gigantea).

Vernonia

Vernonia fasciculata

smooth ironweed [Blooms: Jun-Sep]

Tall ironweed's inflorescence is a flat-topped panicle arising from the tip of the central stem; it is 6-16" across, open and spreading. There are 10-30 disk florets in a tall ironweed flowerhead. The base of the flowerhead is covered by several series of dark colored, broadly oval appressed bracts (phyllaries), often with fine hairs around their edges. The disk florets have tubular, trumpet-like corollas with five recurved lobes; ray florets are absent. Tall ironweed has a much more "open" composite flowerhead than the other ironweeds in Jackson Park, with the trumpet bases of the disk florets easily visible. The fruits are naked, gray or brown, bullet-shaped seeds with a tuft of both short and long tawny or pale purple hairs. To sort out the Jackson Park ironweeds: (1) if both leaves and stem are densely covered with fine white hairs, the leaves are about 3-4 times longer than wide, and each flowerhead has more than 30 disk florets, it's Missouri ironweed (V. missurica). (2) If both leaves and stems are hairless, there are less than 30 disk florets, and the leaves are narrow (typically a half inch or less; about 6-10+ times longer than wide), it's smooth ironweed (V. fasiculata). (3) If the stems and leaves have only short hairs, there are less than 30 disk florets, and the leaves are about 2" wide and 4-6 times longer than wide, it's tall ironweed (V. gigantea).

Vernonia

Vernonia gigantea

tall ironweed [Blooms: Jul-?]

At the tip of a Missouri ironweed stem, a corymb of composite flowerheads (the inflorescence) is produced. The stems of the inflorescence are also covered in fine white hairs and usually reddish brown in color. Individual flowerheads are magenta and rayless; ray florets are completely absent. Flowerheads contain 32-60 disk florets, each 1/2-3/4" across, which have rounded or broadly angled bracts (phyllaries) with sharp tips, dull green or reddish brown in color, that are layered like fish scales around the base. To sort out the Jackson Park ironweeds: (1) if both leaves and stem are densely covered with fine white hairs, the leaves are about 3-4 times longer than wide, and each flowerhead has more than 30 disk florets, it's Missouri ironweed (V. missurica). (2) If both leaves and stems are hairless, there are less than 30 disk florets, and the leaves are narrow (typically a half inch or less; about 6-10+ times longer than wide), it's smooth ironweed (V. fasiculata). (3) If the stems and leaves have only short hairs, there are less than 30 disk florets, and the leaves are about 2" wide and 4-6 times longer than wide, it's tall ironweed (V. gigantea).

Vernonia

Vernonia missurica

Missouri ironweed [Blooms: Jul-Oct]

American wisteria's flowers occur in showy terminal racemes. The flowers have 1/2" long pedicels that are densely covered with stiff hairs and some club-shaped, stalked glands. Individual flowers consist of a 1/4-3/8"white to pale green, hairy calyx and 15-20 mm long bluish-purple, pea-like, hairless flowers. The expanded portion of the banner (or standard) is bent backwards so it is perpendicular to the axis of the rest of the flower; the two lateral petals cover the keel like a hood. There are 10 stamens with tiny anthers, an ovary encircled by a nectar gland, and a single style hidden within the keel; nine of the 10 stamens are fused to each other, the tenth is free. The fruits are 2.75-4" long pea-like, hairless green pods containing 4-8 kidney-shaped or oval seeds, each about 8 mm wide; the pods are brown and the seeds are black when mature. The seeds contain an alpha-amino acid called canavanine which is structurally similar to L-arginine and the pods contain a saponin called wisterin; neither is a good thing to ingest. I've only seen American wisteria growing on the fence west of Japanese Garden. Periodically, the Park District cuts it down, I suspect because they fear for the fence's structural integrity (it's a heavy plant), but I wish a better solution could be found given American wisteria's rarity.

Wisteria

Wisteria frutescens

American wisteria [Blooms: May-Oct]